Considering this is a diagnostic tool that doesn’t require any sophisticated equipment and can be measured easily in children of all ages, our findings add a great deal of evidence to the argument for incorporating CRT into the standard evaluation of all acutely ill children worldwide.
- Dr Susannah Fleming, Nuffield Department of Primary Care Health Sciences, University of Oxford.
A capillary refill time (CRT) of 3 seconds or more is an important warning sign for serious illness and risk of death in children, a systematic review of 24 studies on over 53,000 children has concluded.
CRT is widely recommended as part of the routine assessment of unwell children. It is a simple test to measure the time taken for colour to return to an external capillary bed after pressure is applied, typically by pressing the end of a finger with the thumb and forefinger. Normal capillary refill time is usually 2 seconds or less.
Published in PLOS One, the review led by Dr Susannah Fleming, a research fellow in the University of Oxford’s Nuffield Department of Primary Care Health Sciences, is the first comprehensive and systematic assessment of the diagnostic value of the CRT test for a range of serous outcomes in children worldwide.
A standard method:
This research follows a previous systematic review by the same authors, published in Archives of Diseases in Childhood in 2015, that recommends a standardised CRT method of measurement be adopted internationally:
Press on the finger for five seconds using moderate pressure at an ambient temperature of 20–25 degrees Celsius. A capillary refill time of three seconds or more should be considered abnormal.
The results show that an abnormal CRT of 3 seconds or more increases the likelihood of a serious outcome including death and dehydration – however a normal CRT does not make a serious outcome less likely. The authors conclude that a normal CRT should not be used to rule out serious illness in children, and repeated measurement is important before clinicians should get alarmed.
Commenting on the study findings, Dr Susannah Fleming said:
“We looked at studies across a variety of outcomes including primary and secondary care, low- and high-income countries, and emergency services. We found that a prolonged CRT acts as a useful red flag in all these different situations. Considering this is a diagnostic tool that doesn’t require any sophisticated equipment and can be measured easily in children of all ages, our findings add a great deal of evidence to the argument for incorporating CRT into the standard evaluation of all acutely ill children worldwide.”
“The most convincing data was found for predicting death in settings with particularly high mortality rates, where children with a prolonged CRT had a 4-fold greater risk of dying compared to those with a normal CRT - though this may not generalise well to areas with low mortality. In the studies we looked at in high-income settings, we found abnormal CRT was linked to significant dehydration, reaffirming the importance of routinely measuring CRT in children with suspected dehydration.”
The authors note that CRT specificity may vary for certain diseases, so it was less useful for meningitis than for sepsis, dengue, hypoxia or the need for hospital admission for serious infection.
The research was funded by the European Union Seventh Framework Programme.
Susannah Fleming was funded by a National Institute for Health Research (NIHR) School for Primary Care Research Fellowship.